diff --git a/requirements-dev.txt b/requirements-dev.txt
index f02b3d007..c6fe037d4 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -14,7 +14,7 @@
 
 virtualenv>=12.0.1
 pytest
-pytest-subtests
+pytest-subtests!=0.14.0  # https://github.com/pytest-dev/pytest-subtests/issues/173
 wheel>=0.27.0
 pypiwin32; sys_platform == 'win32'  # pip-only
 
diff --git a/src/natcap/invest/urban_nature_access.py b/src/natcap/invest/urban_nature_access.py
index abdaaab8a..b71948bb3 100644
--- a/src/natcap/invest/urban_nature_access.py
+++ b/src/natcap/invest/urban_nature_access.py
@@ -69,7 +69,8 @@
             'projection_units': u.meter,
             'about': (
                 "A map of LULC codes. "
-                "All values in this raster must have corresponding entries "
+                "Each land use/land cover type must be assigned a unique integer "
+                "code. All values in this raster must have corresponding entries "
                 "in the LULC attribute table. For this model in particular, "
                 "the urban nature types are of importance.  Non-nature types "
                 "are not required to be uniquely identified. All outputs "